Android phone? Mine was doing same - it was because I hadn't set up Google Pay. Sorted that and it worked first time.
Well that was easy found email, it came from do not reply box office rather than memberships, google pay installed card registered we’re in get darn wit kids ! Alternatively see me outside Ponty scratching mi bonce
I had an e ticket for the season launch thing though, so it can't be that. And I've just tried @Sparky a suggestion and that hasn't worked either. Never mind, I've got my session ticket.